Mechanical stoker



Filed March 6, 1929 2 Sheets-Sheet l May 29, 1934. c. T. DENKER MECHANICAL STOKER Filed March 6, 1929 2 Sheets-Sheet 2 Patented May 29, 1934 UNITED STATES PATENT OFFICE MECHANICAL STOKER- Charles T. Denker, Chicago, Ill., assignor to Loraine L. Denker, Chicago, Ill.

My invention relates to mechanical stokers and one of the objects of the invention is to provide an improved mechanical structure which is comparatively inexpensive to manufacture, simple in i 1 construction and highly efficient in operation.

Other objects of my invention will appear hereinafter.

Referring to the accompanying drawings Fig. ,1 shows a view in side elevation of a stoker structure embodying my invention positioned in operative relation to'the firebox of a boiler.

Fig. 2 is a transverse vertical section on the line 22 of Fig. 1. l

Fig. 3 is a top plan view of two of the grate 1 units or sections, and

Fig. 4 is'a sectional view through the two units on the line 44 of Fig. 3.

In the drawings the walls A and roof or arch B are intended to represent the usual firebox or 2 dutch oven construction of a boiler such as commonly used in connection with mechanical stokers.

The base or floor portion C has a central longi-' tudin l depression D formingthe usual ash pit below the grate or stoker. The lower front wall portion of the firebox is open so that the stoker can be moved into and out of the firebox forthe purpose of repairs and to enable easy access to the firebox when repairs to the fire brick or arches are necessary. For this purpose I arrange the 3 16111111? stoker structure on a carriage as a selfcontained unit which may be bodily moved out of its relation to the firebox. This is conveniently accomplished by providing rails E spaced on the floor adjacent the walls and supporting the entire The wheels are carried at the ends of horizontal shafts 2 which are mounted in bearings at the lower ends of legs 3 on each side of the carriage.

- In the present embodiment of my invention all- 40, of the parts relating to the stoking or firing operations mechanicallyare mounted on a frame or carriage. The supporting frame or carriage is substantially the width of the firebox althoughsufficient clearance is left between the firebox.

walls and the sides of the carriage for operating the grate mechanism. The supporting frame itself comprises two long upstanding side members 4 spaced apart in. parallel relation and extending.

structure on wheels 1 which travel on these rails.

is positioned across the top of the frame members at their extreme forward end. The hopper itself maybe of any suitable construction for the purpose. That shown in the drawings has end walls,

an inclined front wall and a vertically disposed rear wall which closes the opening in the front wall of the firebox. This hopper is in position to discharge coal across the grate or fuel supporting bed at the front end thereof where it is received by the forward end of the grate and progressed along the grate to the rear end thereof.

In the present embodiment of my invention the grate or fuel supporting bed is made up of a plurality of individually rotatable units or sections disposed transversely of the frame and to arranged in parallel relation. These grate units are in the form of cylindrically shaped drums F occupying the space between the side members of the frame and positioned with their peripheries as close to each other as possible, the clearance between these units being just sufficient to compensate for expansion underoperating conditions. They are mounted in the frame with their axes in a substantially horizontal plane and positioned so that their peripheries are close to the top of the frame. Collectively the upper portions of the surfaces of these grate units form a substantially continuous fuel supporting bed or grate extending from the front to the rear end of the frame, and occupying substan- 3 tially the width of the frame.

Each of these grate units is made up of a plurality of wheel shaped castings 8 of the same diameter, assembled on a transverse shaft 8 thus forming collectively a drum or cylinder. The individual wheels have hub portions 9 which have square central openings or bores for the correspondingly squared shafts 8. The bores are so proportioned that the wheel members have a relatively loose sliding fit. upon the shaft whereby they may be readily assembled or removed from said shaft. This construction serves to spline or key the wheel members to the shafts for rotationthereby. Radiating from the hubs are the spokes 10 which carry at their outer 100 ends the ,flanges'or rims 11. These flanges are substantially of the same length as the hubs so that when the hubs are placed end to end on the-shaft the edges of the flanges almost abut each other. In making these castings no 05 particular provision need be made to accurately space them apart. Sufficient clearance or space between them need only be allowed to permit expansion when the grate is in operation.

The central portion 11 of the rim or flange 110 which lies in the plane of the spokes is preferably solid or continuous circumferentially of the wheel whereas the remaining portion of the flange on each side of said central portion is provided with deep edgewise slots or openings 12. These slots are open at their outer ends and they extend radially through the rim, communicating with the space within the wheel. In the present construction the slots of one wheel member are alined with the corresponding slots in the adjacent wheel members, and are preferably equally distributed around the peripheries of the wheel members, and since they communicate with the interior of the hollow drum which is thus formed by the assembly of a plurality of these wheel members, they form draft or grate openings through which air is admitted to the fuel supported on the bed. The fine ash resulting from the combustion of the fuel will fall into the drums, through the openings in the upper portions and will be discharged into the ashpit below through the openings in the lower portions of the drums. The rotation of the drums agitates the ash within the drums and thus causes it to fall through said openings, keeping the drums clear of ash at all times.

The wheel members are preferably made in one piece as a single casting. They are preferably all alike and being identical in construction they are readily interchangeable throughout any part of the grate. A very great advantage of the construction lies in the fact that should the grate become burned or damaged in spots, repairs may be readily made by removing the burned or damaged wheel members from the particular drum and substituting new wheel members therefor, without the necessity of disturbing the entire grate structure.

The grate drums are all rotated in the same direction and preferably at the same speed so that the fuel which rests upon their upper surfaces is constantly being progressed towards the rear end of the stoker. The fuel is fed from the hopper at the front end of the grate and is carried along the grate to the rear end thereof. The upper side of the bed of fuel will be more or less level. The fuel will also occupy the downwardly converging spaces formed between the adjacent upper portions of the peripheries of the drums, but the movement of these adjacent surfaces of the drum peripheries is opposite. Hence while the movement of one drum tends to carry the fuel downwardly into this space the adjacent surface of the next drum tends to carry it upwardly and out of this space. The result of this action is that the under portion of the bed of fuel is constantly being agitated and tumbled about or turned over in such manner that the ash or burned fuel is readily released from the bed to drop down through the openings in the grate members, thus constantly presenting live fuel to the draft openings. Each drum member is constantly bringing clean draft openings into position and carrying away the ash or burned fuel from the under surface of the fuel bed, thus causing the fuel to be burned at its highest efiiciency. A particular advantage of my present construction lies in the fact that no portion of these surfaces remain very long in the heat zone of the burning fuel. Due to the fact that the grate members are individually rotatable they constantly bring cool portions of their peripheries into the heat zone, hence the damage due to burned or warped grates is very materially reduced.

The grate members may be rotated by any suitable mechanism for the purpose. In the present construction the shafts 8' are mounted in bearings 13 and 14 in the side members 4 of the frame.

- At one side of the frame the shafts extend through their bearings and carry gear members 15 on their ends. These gears mesh with intermediate gears 16 mounted on suitable studs on the side of the frame and preferably arranged in the plane of the axes of the shafts. This train of gears thus serves to drive all of the grate members in the same direction and at the same speed. In the drawings I show a motor 18 mounted on a bracket 19 on the front end of the carriage and connected to drive the train of gears through the intermediate gear 20 which is positioned between the first gear 15 of the train and the pinion 21 on the motor shaft. The guard flange 22 may be extended along the frame above the gears to prevent coal or ashes from dropping into the gear train.

Along upper edges of the side members of the frame I provide the flange members 23 which rise slightly above the plane of the grate surface and support the edges of the bed of fuel. These flange members incline outwardly and upwardly and into close relation with the walls of the firebox to prevent fuel from falling between the carriage and the firebox walls. These guard flanges have a series of slots 24 which form draft openings and serve also to keep the flanges comparatively cool. The guard flanges are preferably made of separate pieces which are bolted at 25 to the side of the frame so that in the event they become damaged or burned they may be readily removed and replaced.

At the rear end of the frame I provide a dump grate 26 which is positioned between the last grate drum and the end of the carriage and upon which any clinkers which have formed may be deposited from the last grate drum. This dump grate is preferably in the form of a flat plate having suitable draft openings 27. It is positioned transversely of the frame and horizontal. At its rear edge it is pivoted at 28 to swing downwardly and dump its contents into the ash pit when desired. The dumping of this grate is accomplished by a control rod 29 which is pivotally connected at its rear end 30 to a downwardly extending arm 31 on the under side of said grate. The forward end of this arm has a suitable handle 32 by which it may be manipulated from the front end of the stoker.

It will be obvious to those skilled in the art that my invention may be embodied in other structures without departing from the spirit of the invention, and I desire it to be so understood.

I claim:

1. A grate unit for mechanical stokers com prising spaced side members, shafts journaled in said side members and extended therebetween, wheel members mounted on said shafts in side by side relation and held against rotation relative to said shafts, the wheel members on adjacent of said shafts having the peripheries thereof in close juxtaposition yet sufficiently spaced from each other to prevent inner engagement of said wheel members upon expansion thereof in the use of the grate, each of said wheel members comprising a hub, a rim, and medially located spokes interconnecting said hub and rim, each of said rims having slots extending inwardly from the side edges thereof, the rims of adjacent wheel members on the same shaft being spaced from each other to provide an air space and the slots extending inwardly from the edges of the rims 159 of adjacent wheel members on the same shaft being aligned with each other to provide air spaces,

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the spaces between the edges of the rims of adjacent wheel members and the aligned slots in adjacent wheel members providing ample air space to afford good circulation of air to prevent burning of the edges of said rims.

2. A grate unit for mechanical stokers adapted to be mounted in a fire box having refractory each other to prevent interengagement of said wheel members upon expansion thereof in the use of said grate unit, flanges on the upper edges of of said side members and extending therefrom toward said refractory walls, said flanges including inwardly inclined portions having openings therein, the inwardly inclined flanges preventing clinkers from engaging the refractory walls of the fire box to prevent clogging of the grate and the openings in the inclined portions of the flanges affording ample circulation of air to thereby reduce the temperature of the refractory walls of the fire box to prolong the life thereof, said inclined flanges also preventing material on the grate from scoring said refractory side walls.

CHARLES T. DENKER. 

